Wally626

Wally626

Joined on Oct 2, 2011

Comments

Total: 88, showing: 1 – 20
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On What is equivalence and why should I care? article (2001 comments in total)
In reply to:

Wally626: Equivalence in general works, but tends to break down on the margins. Yes a 50mm f/1.4 lens in a m4/3 camera at ISO 100 can get close to the same image as a 100mm f/2.8 on a FF camera at ISO 400, even more similar if both are 16 MP sensors. So same number of pixels, same DoF, roughly same noise level at both pixel and total image levels, same perspective, same shutter speed. However, this assumes a perfect lens, the m4/3 lens has to have a better resolution than the FF lens, or both have to be better than their sensors. It also falls apart if you stick a f/1.4 lens on the FF, what m4/3 is equivalent? Or your have a Nikon 800 with 36 MP, etc.

It is also easier to make a sharper lens for a smaller image circle which helps. Phone lenses are in general very sharp in terms of lines per mm, but of course have very few mm to work with.

Direct link | Posted on Jul 7, 2014 at 19:40 UTC
On What is equivalence and why should I care? article (2001 comments in total)

Equivalence in general works, but tends to break down on the margins. Yes a 50mm f/1.4 lens in a m4/3 camera at ISO 100 can get close to the same image as a 100mm f/2.8 on a FF camera at ISO 400, even more similar if both are 16 MP sensors. So same number of pixels, same DoF, roughly same noise level at both pixel and total image levels, same perspective, same shutter speed. However, this assumes a perfect lens, the m4/3 lens has to have a better resolution than the FF lens, or both have to be better than their sensors. It also falls apart if you stick a f/1.4 lens on the FF, what m4/3 is equivalent? Or your have a Nikon 800 with 36 MP, etc.

Direct link | Posted on Jul 7, 2014 at 16:03 UTC as 317th comment | 2 replies
On Surf's Up: Clark Little's incredible wave photography article (54 comments in total)

When a youth I went to Hawaii and me and a friend decide to body surf shore waves on Maui. When the big waves hit near the shore is was amazing, Standing in waist deep water, then bare sand, then crushed and spit up on the beach. Usually followed by the next wave whacking you in the head. Cudos for taking pictures in that type of surf.

Direct link | Posted on Jun 30, 2014 at 12:33 UTC as 13th comment
On Sony Alpha 7S added to test scene comparison tool article (272 comments in total)
In reply to:

Mike FL: FWIW:

Hopefully, this will start a new trend for all the manufactures to reduce the megapixels for sensors of all size for the sack of IQ.

The revolution of the A7s is not really in still images. It is a fine low light camera and will have very low per pixel noise compared to other cameras, but is not that much better or not better than the Nikon D4s and other FF bodies when the images are scaled to the same output. At low ISO the A7 or A7r would both be better as would many other cameras. Where the A7s is revolutionary is in the video. Being able to use all the pixels (at least from the 16:9 crop) gives the camera much more low light ability than any other camera available to consumers. It is not a difference of 10 or 20% it is several stops of difference.

Direct link | Posted on Jun 20, 2014 at 18:35 UTC
On Sigma 50mm F1.4 DG HSM | Art Lab Test Review preview (555 comments in total)
In reply to:

Frank_BR: I do not know why so much importance is given to distortion and vignetting, which can be easily corrected by software, provided they are not excessive.

It also seems a bit amateurish that a laboratory as DXO Labs can not discount the effect of the camera sensor on the test of a lens. Lenses that are tested today will continue to be sold for several years, but the DXO Labs results will be obsolete tomorrow because the sensors are continuously being improved.

There is a MTF value for the sensor by itself but I do not know of anyone who publishes it or measures it directly. The easiest method would be to measure the lens separately then measure the lens sensor combination then divide by they lens value. The combined value is just the product of the two separate measurements. So if the lens is 0.8 and the sensor is 0.95 (at a given frequency) then the overall value would be 0.76. I think in practice the sensor is near 1 for most of the frequencies used. A 24 MP sensor on FF has 4000 vertical pixels, so 167 pixels per mm, or 83 pixel pairs per mm. Depending on how one approaches the issues of sampling and such as well as issues such as antialiasing filters as well as sensor leakage you should end up with pretty good but not perfect resolution with samples of 40 line pairs per mm, which is normally the sharpest tested. With 2X oversampling the 24 MP FF is good to 42 lp/mm. A 36 MP sensor would get you 51 lp/mm.

Direct link | Posted on May 28, 2014 at 18:02 UTC
On Sony Cyber-shot DSC-RX100 III First Impressions Review preview (2978 comments in total)
In reply to:

Beckler8: This is more like a variation than an upgrade model. Video gets a big upgrade but audio, with no hot shoe and no mic input gets a huge downgrade. (Don't bother mentioning external recorders.) As the review points out, some will like the lens variation. Others, like me, would much prefer more/longer zoom range at the expense of lens speed. Not everyone wants maximum low-light performance at the expense of being able to do nothing zoom-wise...yes, 2.9x zoom is essentially nothing, esp. in video where presumably none of the smart digital zoom is usable. I'd gladly trade the flash for the hot shoe too! There must be a way to have both though. Anyway on a camera of this stature then, there needs to be 2 (or more) versions, catering to different preferences.

There are 3 versions of this camera, plus the RX10 if you really need the better video plus hot shoe plus clickable or non-clickable aperture and of course the 24-200mm equivalent f/2.8 lens.

Direct link | Posted on May 16, 2014 at 14:19 UTC
On Sony Cyber-shot DSC-RX100 III First Impressions Review preview (2978 comments in total)
In reply to:

discbrake: Good job, Sony. But OM-D E-M1 over RX100 III for a walk-around camera. E-M1 is "small" for me. I'm more excited for the Alpha 7s that will release in July.

The A6000 with 16-50mm kit lens has roughly the same equivalent aperture in terms of total light, DoF effects and focal length as the RX100mIII. Cost the same amount of money, but the A6000 is larger and heavier, not as good video quality and no built in ND filters. So larger more versatile camera if you buy extra lenses versus small compact camera. Seems to be a fair trade to me. My wife would prefer the RX100mIII and I the A6000.

Direct link | Posted on May 16, 2014 at 13:44 UTC
On Sony announces pricing and availability for Alpha 7S article (131 comments in total)
In reply to:

Thorgrem: How does this compare to the much cheaper Panasonic GH4?

4K requires external recorder. Quality will be higher than GH4 especially in low light, but will cost more and be a larger total package.

Direct link | Posted on May 16, 2014 at 13:05 UTC
On Olympus PEN E-P5 Review preview (494 comments in total)
In reply to:

l_d_allan: I wonder if such a work-around would apply to the Sony A7 shutter-slap issue?

Just the A7r, the A7 has electronic first curtain shutter to eliminate the shutter shock issue.

Direct link | Posted on May 15, 2014 at 12:40 UTC

Seems like the close shutter, open shutter, wait, use EFC might result in less vibration in images but it would seem to introduce more lag between shutter button push and the actual image being taken. Nice thing about EFC as used by Sony and I assume the other makers is that the delay between shutter press and image recording becomes very short.

Direct link | Posted on May 14, 2014 at 15:45 UTC as 16th comment | 2 replies
On Did Amazon just patent the seamless background setup? article (133 comments in total)

The patent discusses some specific light placement, but in the end it is: get a white background, flood it with light, place object on semi-transparent table, take picture. The novelty may be in the specific light and baffle placement, but otherwise it has been done for a long time.

Direct link | Posted on May 7, 2014 at 12:31 UTC as 36th comment
In reply to:

Victor Engel: Not 500 times longer than in NYC but 500 times longer than in the previous facility, which happened to be located in NYC.

What has cave paintings got to do with anything?

Mentioned in the video that they hope to preserve the images for 2000 years. So 1/500 would be 4 years. Some math errors there somewhere, I expect most prints would do good for 40 or 50 years in a typical home environment, so more like 20,000 years if 500 times.

Direct link | Posted on May 2, 2014 at 15:57 UTC
On Sony a6000 First Impressions Review preview (899 comments in total)
In reply to:

JaimeA: Mr. Jeff Keller:
Please make sure to mention the omission of the electronic level in your report/review of this important camera.
The level is an essential tool. I still cannot understand why it has been removed.

Now that the camera has the standard hot shoe you can buy one of these hot shoe bubble levels. I will grant I have used the electronic level a few times on my Sony but not enough I would not buy the camera over it.

Direct link | Posted on Apr 23, 2014 at 19:35 UTC
In reply to:

photophile: "3 separate built in LCD monitors for camera settings and metadata entry. Large 10 inch screen folds out for full resolution HD monitoring with wide viewing angle and high brightness."

Battery life ?

Looks like a pretty big battery hanging off the back.

Direct link | Posted on Apr 7, 2014 at 19:56 UTC
In reply to:

Random Asian Guy: A lot of my photos are from low light situations, So this camera interests me quite a bit.

But I'm surprised it can only manage 5 fps for stills with only 12 megapixels.

Speculation is it using the A7 shutter, which may not be able to handle much more than 5 fps. I would think the electronics side could do it. Maybe too much shutter shake at high speeds, lot of moving mass in a small body to damp 10 times per second.

Direct link | Posted on Apr 7, 2014 at 15:58 UTC
On Apple applies for dual-sensor camera patent post (71 comments in total)
In reply to:

agentul: Panasonic has been making video cameras with three sensors for years.

Three sensor camera are quite common in the high end of video, but it does the opposite of the Apple invention. Three sensors requires a splitting prism system and a much deeper camera.

Direct link | Posted on Mar 26, 2014 at 13:27 UTC
On Apple applies for dual-sensor camera patent post (71 comments in total)

Apple also introduced the two color flash, which I hope could be translated to larger camera flashes at some point. Being able to match the room color temperature does make for nice images. It can be done today using the correct gels over the flash but is a much slower process then an automatic flash system that can change color by using a ratio of the power from different color lamps.

So will this be followed by a four camera system with one camera for each color plus B&W?

Direct link | Posted on Mar 26, 2014 at 13:25 UTC as 25th comment | 3 replies
On Sony Cyber-shot DSC-RX10 Review preview (491 comments in total)
In reply to:

J Parker: Initially I thought this camera was expensive -- then I realized it might be dollar for dollar one of the best camera values around.

If the Zeiss lens is as good or better than the f2.0-2.4 from the days of the Sony F707/717/828, this is tremendous value for the money. Consider the cost of a Canon or Nikon F2.8 24-200mm lens combination -- then ask yourself how much would a Zeiss equivalent would cost.... To add a little more food for thought, years ago, Luminous Landscape did a shoot out between the above mentioned Canon L Glass and the fixed Zeiss lens on the Sony F828. The Canon should have won hands down -- it was a dead heat.

Think about the sum of the parts this camera offers. This camera is worth every dime.

The 18-XXX APS-C lenses are a bit tighter than the RX10 at the short end and slower at the long end. 18mm on Nikon or Sony is 27mm FF field of view.

Direct link | Posted on Mar 20, 2014 at 19:33 UTC
On Sony Cyber-shot DSC-RX10 Review preview (491 comments in total)
In reply to:

tlinn: The very interesting discussion of "equivalent" aperture on page 1 left me with a question. I totally understand that f/2.8 on a smaller sensor provides less control over DOF than the same aperture on a larger sensor. But Jeff seems to state that there is also a difference in the amount of light let in. Is he simply stating the obvious—that more photons are allowed through the larger opening thereby improving image quality? If so, am I correct in assuming that the conversion table of equivalent apertures only seeks to account for the difference in DOF?

To extend on Richard, the total amount of light can be associated with the total amount of noise in a image. Aperture equivalents for DoF and Noise can be done but there are some assumptions made when doing so that not all cameras or sensors are going to be able to meet. In essence you are assuming a perfect lens and a perfect sensor or at least one with enough pixels to use the same proportional circle of confusion as the larger sensor and a lens that can project a sharp enough image onto the sensor so the image details are smaller than the chosen CoC. It also assumes that the technology in terms of noise is similar in the various levels of sensors. Not a bad assumption as some of the smaller sensors do have better noise performance per unit area than the larger sensors.

Direct link | Posted on Mar 20, 2014 at 19:25 UTC
On Sony Cyber-shot DSC-RX10 Review preview (491 comments in total)

Nice shot of the Reading Room at the Suzzallo Library. Spent way too much time in that room. Reading books and writing on paper. You youngsters may not remember, but that is what was done before Kindles and iPads.
If Sony can get the price of this camera down to $999 That would really increase sales, so many threads on DPR start "I have $1000 to spend on a camera".

Direct link | Posted on Mar 20, 2014 at 19:15 UTC as 128th comment | 1 reply
Total: 88, showing: 1 – 20
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